To a developing device included in an image forming apparatus utilizing electrophotography, such as a photocopier, a facsimile machine, and a printer, a toner is supplied using a toner container (developer supply device) which is detachably provided to the image forming apparatus. Conventionally, for realization of a preferred supply of toner from the toner container to the developing device, various kinds of toner containers have been suggested.
For example, patent document 1 (Japanese Laid-Open Patent Application No. 2000-250298 (published on Sep. 14, 2000) discloses a toner container in which a supply opening (toner supply port) is formed through the bottom surface of the toner container (toner storing member). In this developer supply device, toner in the toner container is agitated by an agitator provided in the container, so that aggregation (coagulation of toner) is prevented. In the developer supply device, furthermore, a position where the agitator stops rotation is controlled so that the resistance arising on the occasion of rotating the agitator again is decreased.
However, the developer supply device of patent document 1 is not provided with a shutter for opening and closing the supply opening. For this reason, toner drops off through the supply opening at the time of detaching the developer supply device.
When the toner in the toner container runs out, the toner container is typically replaced with a new one or is refilled with toner. In such cases, the toner container is detached from the image forming apparatus or the developing device. In this connection, there are measures for facilitating this operation and preventing the toner from scattering around.
One of such measures is a seal on the opening (toner supply port) for supplying the toner.
Since the toner supply port of a new toner container is sealed with a seal, the toner does not scatter around through the toner supply port.
Meanwhile, in a case where the toner container is replaced with a new one after the toner runs out, an amount of toner remaining in the old toner container is scarce. For this reason, in such a case, it is often considered unnecessary to operate, for instance, a shutter for preventing the toner from scattering through the toner supply port. However, in many cases a few amount of toner remains inside the toner supply port. Since such toner scatters through the toner supply port, it is necessary to provide, for instance, a shutter for shutting the toner supply port.
The toner container is sometimes detached on the occasion of troubles such as device malfunction. That is, the toner container may be detached even if toner still amply remains therein. In such a case, the toner is likely to scatter at the time of detaching the toner container.
In order to prevent the aforesaid scattering of toner, most of the toner containers are equipped with a shutter mechanism by which the toner supply port is opened and closed.
Meanwhile, there is a type of toner containers in which the toner container is rotated for discharging toner from the toner container to the outside. Such a toner container is provided with a space where the toner discharged through the exit of the toner container is temporally stored. Then the toner discharged from the exit is supplied from the space to the toner supply port, on account of the rotation of the toner container.
However, the rotation of the toner container of the aforesaid type of toner container stops at an arbitrary position. In other words, at what position the rotation stops is not particularly determined. On this account, when the rotation of the toner container stops at a particular position, the shutter or the like for opening and closing the toner supply port may not properly operate.
Moreover, in the aforesaid type of toner container, toner flows into the space for temporally storing the toner, when the rotation of the toner container stops at a particular position. If a long period of time elapses while the toner remains in the space, the toner in the space coagulates and do not flow out. For instance, in a case where the rotation of the toner container stops while the exit for supplying toner from the toner container to the toner supply port is below the upper surface (boundary surface) of toner (i.e. the exit is immersed in the toner), the toner flows into the space through the exit, because of the weight and pressure of the toner. If a long period of time elapses while the toner remains in the space, the toner coagulates in the space and do not flow out therefrom, on account of a pressure due to the weight of the toner and a pressure generated when the toner flows (rushes) into the space. This induces such a problem that the toner is not stably supplied when the operation of supplying the toner is resumed.